The levels of territorial detail The Web access system to the official data on present population coming from the 14th General Population Census and General Housing Census is based on the Italian administrative subdivisions, in particular (from the less detailed to the most detailed level): Italy, geographical areas, regions, provinces, municipalities. The system allows to specify at the same time both the territorial area of interest (for example Central Italy, Calabria region, the province of Treviso, etc.) and the level of territorial detail (for example regional, provincial, etc.). The combination of an area and a level of detail makes a territorial context. Hence, examples of territorial contexts are the regions of Central Italy, the provinces of Calabria, the municipalities of the province of Treviso. The system is based on the hierarchical structure of territorial contexts: each region "contains" a number of provinces, which "contain" a number of municipalities. It is possible to browse the territorial hierarchy, by increasing or decreasing the information level of detail. For example, if the chosen territorial context is the region of Central Italy, it is possible to increase the level of detail to the provinces of a specific region (for example, the provinces of Toscana) or to a coarser vision of the phenomenon, by considering data relative to all the Italian geographical areas. For the sake of statistical significance of data and privacy protection, only a few tables are available at the municipality level. The system is however able to guide users by allowing them to select only the tables compatible with the chosen territorial context.